Mark Updegrove is the director of the Lyndon Baines Johnson Presidential Library and Museum in Austin, and the author of "Baptism by Fire" and "Second Acts." His latest book is "Indomitable Will: LBJ in the Presidency," a portrait of Johnson through the stories and recollections of the people who were with him during his presidency. Updegrove recently talked with Chronicle reporter Joe Holley in the office Johnson used at the library.

Q. How do you describe the format of the book, and what were you hoping to achieve by taking that approach?

A. I think it's very difficult to know Lyndon Johnson, to get to know this enigmatic man, and I think the best way to understand who he was and how complex he was is by seeing him through the eyes of those who knew him. It's my view that there were as many LBJs as there were people who knew him.

Q. Who was it in your book who observed how Johnson during a typical day made a huge number of crucial decisions?

A. It was Yoichi Okamoto, his photographer, who had unlimited access to him, and he would see these decisions that he had to fire off at any given moment and how incredibly important they were. I think he exercised power with reflexive ease, but you could see the burden it would take on any human being. You could certainly see the toll it took on Johnson.

Q. When you see photos of him, it's hard to realize that he was still a relatively young man in the White House. He was only 64 when he died, but he always seemed old to me.

A. He was 55 when he took office, and he died less than 10 years later. As Larry Temple, who was his White House counsel, will tell you, he was the oldest man in town when he came back to Austin. He looked old. And that's the reason that he didn't run for office again.

And there's a great misconception about that. People think that he was beleaguered and embattled, or he just sort of waved the white flag and said, "I'm done, I'm outta here," but that's not it at all. He decided well before that he wasn't going to run again, because he was concerned about his heart. He had a genetically weak heart. He didn't want to put the country through what might have been a health crisis, as did Woodrow Wilson and Franklin Roosevelt.

Q. Someone described him as a 'creature of excess' - planes, cars, TVs ...

A. Appetites.

Q. Could anyone, whether it was Lady Bird or anyone else, temper those appetites?

A. With Lady Bird, I think that they were a package deal, and you can't understand one without the other. They had a very symbiotic relationship, and as I said in the book, I think her equanimity helped to calm his storms. Her grace helped to smooth out his rough edges.

Q. How did those gargantuan appetites affect his presidency?

A. He had a penchant for micro-management and an ability to process and collate so many things in his mind on a current basis. He would watch three television sets. He had a teletype machine in the Oval Office. He would monitor news intensely. It manifests itself in his presidency by his manic energy and his sheer capacity for work, for getting things done.

Q. It seemed also that he had to do everything right then.

A. In my office is a shadow box containing all the pens that he used to sign bills into law throughout one year, 1965. And it is unbelievable what is in that box. Elementary and Secondary Education. Higher Education. Medicare. Voting Rights. The Immigration Act. Arts and Humanities. Clean Air. Clean Water. Highway Beautification. I don't know of anyone, including FDR in 1933, who had a year like that, because he knew that his political capital and ability to get things done was ephemeral, and he was absolutely right.